Method and apparatus for rolling sheet-like material



y 2% wm 1,6541235 vf. az. mmcalm, m., n-:T AL..

METHOD AND APPARATUS FOR ROLLNG SHEET-LIKE MATERIAL mlllll II Filed Oct. 24, 192'? 5 Sheets-Sheet l lNvENTQR FLMQJW' SIMM, Law 3M bvba.

F'. C. BIGGERT. JR., E'' AL METHOD AND AFARATUS FOR ROLLING SHEET-LIKE' MTERAL mm. L 19m, 125545235 F', BIGGERT, JR., ET AL.

METHOD AND APPARATUS FOR ROLLING SHEET-LIKE MATERIAL Filed. Oct. 24, 192'? s snmwshm s BiGGERT, JR,` AL.

METHOD AND APPARATUS FOR ROLLING SHEET-LIKE MATERIAL Filedpct. 24, 1927 5 Sheets-Sheet 4 R W m Ny/v P m @N l W .M W F. M@ .ww r @Nw K u R mmi u Wm. l Wc@ X NN @NNN M N mmww @MW w m M @N S @w QN um ew uvm: mmf, Nm, wm. mm m @N NN wm NN w NN bmw QM: K 1. Nm, //7. w mm. A mm um mm wm uw E m .5ML m Dec. 27, 1927. l

. F. C. BGGERT, JR., ET AL.

METHOD ANO APPARATUS FOR ROLLING SHEET-LIKE MATERIAL AFiled Oct. 24, 1927 5 Sheets-Sheet 5 INVENTOR Patented nec. 27, 1927,

-iTEo STATES 1,654,235 PATENT OFFICE.

nLoianNoE c. 'Bressan an., or. cnArToN, AND LANE JoHNsoN, or meant,

PENNSYLVANIA.

METHOD AND APPARATUS FOB EtClIIiZIIGrA vSIIElET-LIKIll MATERIAL.

Application ined vcamerali, 1921. semi No. 228,176.

Illhis application is a continuation in part o our application, Serial No. 108,264, tiled A rilQO, 1926.

his invention relates to the rolling of 6 sheet-lilac material and is particularly useful for the rolling ot long lengths of wide sheets, although it is also of great value in the rolling of plates, stripsI and other products ol suhstantially unitorm-thiclrness. ln particulu lar it is adapted for the application of very heavy drafts to wide, thin sections of metal. lt provides a mill which may he operated at high speed and further, provides a continuous rolling mill for rolling metal strips of lpractically unlimited length, and of a ratio of width to thickness which is comparable only to sheet metal as distinguished from plates and strips as ,produced in the past.

Except for recent developments in which 2H accuracy ot control of the shape of roll passes has made it possible to depart therefrom, it has heen the practice in the metal rolling industry to produce sheet metal hy the process of rolling a pair of sheet bars in ,'5 a preliminary step, into rough plate, then heating the plates and rolling them in a paclr` in a mill with two rolls (two high), with such doubling, increasing ot' the layers inthe pack, and reheating as is called for in the 3U opinion of the roller in charge of the mill. In the rolling of strips, in which the length of the piece is not a limitation, as in pack rolling, there has been a considerable 'developmentin the use of continuous mills Si operatinga on the -piece when both hot and cold, but the results have not been satisfactory'from the point of view of producingsheet metal in strip form. lt has been the universal experience of workers in the strip W rolling art, which has always been distinct from the sheet rolling art, that in the greater widthslot product, reductions to thinness comparable with sheet metal has not heen practical. Expressed in other words, noth- 45 insr aplirmiching the ratio of width to thickness ot sheet metal has heen comn'iercially practical te produce on the strip mills of the past.

ln rolling hy the usual methods and with lil the usual mills great difficulty has always heen experienced due to several factors, the most important of which are changes in shape ot the rolls due to the roll neck heating, and changes in the setting of the rolls 6l-l lue to wear ol the hrasses. The pressures developed hetween the necks and the hrasses areso high that sufficient heat is generated to swell the bodies oit' the rolls irregularly land thus adversely ati'ect the contour of the lthe finished productrthe gauge frequently varying from end to end of a single strip.

Our mill is .adapted to the continuous rolling of strip metal, with a sheet ratio of width to thickness, the product being termed for convenience hereinafter as a strip sheet. @ur

-mill is effective for reduction of metal in sheet or strip form, at high speed, with radical reductions in each pass, and hy a continuous rolling process.

By a continuous rolling. process we refer 4 to a rolling process in which the piece passes from one stand of rolls to the next, receiving one pass in each stand, as distinguished from being repassed through the same stand. ln such continuous rolling process the piece may he engaged but by a single roll stand at a time, or it may be engaged by two or more successive roll stands at the same time.

The use of a four high mill having rolls to engage the piece which have small diameters relative to the two outer rolls, which serve to hack up, the smaller rolls and give them rigidity against excessive springing, is more or less familiar inthe art, although not in continuous rolling or strip processes. Such mills give `greater reductions with the same amount of Jforce exerted, than do mills having hut two rolls having the saine strength as the sum ot the strengths of one small diameter roll and one large diameter one, because of the reduced area of metal in surface engagement with the small rolls, as compared to the area which is engaged, the rolls are very large.

ln. hi gh speed mills which are re uired iler use in a continuous process, great ditliculty is experienced in driving the rolls, particularly in the last few stands, The last stands pass a very long strip in the same length of time as a much shorter strip was passed through the tirst few passes. This requires high.'

till

l lill lllll speed whether the piece is hot or cold, and

high speed is also re uired in hot rolling so as to avoid interme iate heating. When the piece is thin and wide, it has a very large,

area in proportion to its mass and radiates its heat very rapidly, and no time can be `lateral pressure on the working rolls. lThis lateral pressure is in a. direction longitudinally of the piece being rolled and in a direction opposite to the direction of rolling.r

By driving the working rolls` this lateral pressure is substantially balanced out and wear on the brasseslof the working rolls is materially reduced. The driving of the working rolls is also of advantage in that'it eliminates'any necessity for maintaining exact ratios of diametersbetween the backing rolls, such as would have to be maintained if the backing rolls were driven positively and the working rolls were driven by friction therefrom. 4-

From the point of view of thin strip rolling, it should be pointed out that a slight defect inthe true contour of the pass between the rolls of a mill, when the piece is between them, will result in reducing the thickness of the piece more at one point than another, and thus increasing the length more alon one line than another. In a long piece suc as a strip, the result of increasing the length morer'along one line than another is much more serious than in the rolling of short pieces because the metal being thin,

, cannot flow laterally, and the defective zone continues to increase in length through the whole body of the strip, in a cumulative manner, thus twisting thevpiece if the increase in length is at one side, which twist is termed camber, or distorting it-if itis at both sides, or buckling the piece if it is in the middle. u c

Itis thus of' particular in'lportance in strip rolling, and of even more importance in continuous strip or strip-sheet rolling, to control the shape of the roll pass very accurately so as to reduce all portions of the metal pro ortionately.

The wi er the piece being rolled', and the thinner its cross section, the more imperative becomes the accuracy of theroll passes, vas will be obvious when the great 4pressures req uired to make an effective reduction are considered, and the increased forces tending to spring the rolls out of shape while acting on` wide metal as compared to narrow metal. l

. It is necessary in a continuous rolling proc- I ess for strip sheets to reduce the metal in any 1one stand so that it is of proper cross sectional size and shape for the succeeding stand. Unless this condition is obtained, the continuous rolling prcess becomes impractical.

The increased tendency of the rolls to spring out of shape under the heavy reductions employed, with its consequent diliculty in controlling the contour of the several passes, may be substantially eliminated by utilizing mill stands having at least one, and preferably two working rolls of relatively small diameter, and backing rolls of relatively large diameter for the working rolls. The working rolls have a relatively small area of contact and the backing rolls ma be made sufficiently large to resist ben ing. But a mill of this character is still objectionable because of roll neck heating. The necks of the backing rolls carry the load and if the lwere equipped with ordinary brasses su cient heat would be generated to swell the backing roll bodies irregularly, and this condition would be reflected through the workin@ rolls and adverselyaifeet the contour ota the pass, rendering control impossible. On this account it is impossible to roll stri sheets continuously in mills equipped wit ordinary brasses, even ifthey were four hlgh, and even in single stands the speed of rolling must be exceedingly slow.

Instead of the usual brasses we provide anti-friction bearings for the necks of the backing rolls. The provision of anti-fraction bearings insures maintenance of a temperature at the backing roll necks sufiiciently` low to substantially prevent distortion of the contour ofthe pass and consequent buckling or wrinkling of the product.

lIt is necessary to-depart from customary mill design in order to accommodate the `antifriction earings. The necks of the backing rolls must be made strong enough to withstand the spreading force, and our exerience has beenthat when anti-friction earings of sufficient size to carry the heavy load in a relatively wide mill are designed for these necks, the require a greater space than is available i the backing roll bodies are dimensioned purely with reirence to the beam strength required. In order to accommodate these large roller bearings, it is necessary to materially enlarge the diameter of the backing rolls relative` to the working rolls over their diameter if calculated as beams. By using relatively small working rolls so .as to limit the spreading force and relatively largebacking rolls'so as to permit of usin adequate anti-friction bearings, it is possi 1e to limit roll neck heating, thus permitting the accuracv of control necessary for continuous rolling processes.

One of the advantages of four high mill ,design is that the backing rolls can be given almost any desired diameter without affecting the power required to operate the mill,

lll

hill

i dll since the engagement with the piece is a tunction of the workin rolls only. lVe are accordingly not limi-te in the size of our backing rolls, and are able to employ ade-' quete antifriction bearings in our mills, whereas in wide two high mills for rolling material of substantially uniform thickness there is not sutcient space to accommodate anti-friction bearings which will carry `the load; this is because in the rolls of a two high mill the neck-s of the rolls would have to be so -large in order to resist the spreading torce that there would. be insuliicient space between them for adequate roller bearings to be mounted.

llt should be noted further that from the point ot view ot accuracy ot reduction, soV

high speed-s called tor in the production ot' strip sheet would be practically impossible.

ln practice. we preier to operate several stands in series so as'to carry out a continuous rolling process. 'l`he material runs straight and true and buckling or wrinlrling ot the strip lsheet is avoided. The rolling may be carried on hot or cold, the anti-triction bearings tinoctioning` in either case to prevent distortion ot the rolls, dueto heatingl ot the roll necks, and inaccurate rolling due to wear on the bearings.

ilnthtriction bearings also serve to materially reduce the power required. rthey are theretore etlective not only tor permitting the continuousrolling ot high quality sheet material, but also tor effecting material economies in the operation of the several stands.

lll/lille embodying only single standsY are highly usetul in rolling operations requiring heavy reductions oi metal, either hot or cold. We will describe our invention with relation to a mill having but two bachlng up rolls, termed by us al 'tour high mill, but it will be understood that the principles ot our invention may apply to mills having more than two backing up rolls. 'ln the accompanying drawings illustrat ing the present preterred embodiment ot our invention as applied to hot'rolling,

Figure l is a diagrammatic view ot a mill tor a continuous'rolling process employing tour high millstands having anti-friction bearings, Y

lligure 2 is a top plan view partly broken away of one of the millstands showing its drive in more detail,

Figure 3 is a trent elevation partly broken away oi. a single stand,

Figure 4 is a top plan view ot the mill stand shown in Figure 3,

Figure 5 is an end elevation thereof,-

Figure 6 is a section partly broken away, taken on the center line ot' the mill and showing the anti-friction bearings for one of the backing up rolls,

Figure 7 is an end elevation to enlarged scale showing the manner ot supporting the working rolls, and

Figure 8 isa horizontal section taken on. the line VIHHVHI ot Figure 7.

Referring iirst to Figure 1 there is shown a seriesot slab heating furnaces F, each discharging onto a roll table 2. The roll table carries the slabs successively to a twohigh mill 3 where the first reduction is eftected. flatter leaving the mill stand 3 the slab is carried by table rolls s to edging rollers 5 and thence to a millstand 6. The sta-nd (l comprises working rolls having baching roll-s ot larger diameter, these backing rolls being provided with anti-friction bearings. y

Yllhe slab is delivered 'trom the stand 6 vto a roll table l and then passes through edging rolls 5a and a second :tour high stand 6a'. Alter leavingl the stand 5a the slab is carried by table rollers lb to edging rollers 5b and another tour high stand 6b..

The sev-eral stands are driven by independent motors i', 7, and 'lb through reduc ing gears 8, tia and 8b. rlfhe reducing gears each drive pinion stands 9 trom which power is talren to both ot the working rolls in cach ot thet'ounhigli stands through spindles l0.

rllhe several stands (i, 6a and 6b are run at progressively increasing speeds so that it a piece ot material' should be long enough to entend through two successive passes at one time the rolling will be properly effected.'

ln operation, the material will not ordinarily be passing through more than one ot the stands 6, t3 or 6b at one time, although it a particularly 'long slab is employed the stands 6a and 6b may both engage the metal at once.

lt will be noted that the gear sets 8, 8* and 8b etlect successively smaller speed re ductions between the corresponding motors and their pinion sets. This permits ot securing the desired'variation in the speed ot the rolls in the several stands with correspondingly less variation inv motor speed.

The material is delivered trom the stand 6b onto a roll table ll. The rollers of this table, instead ot being placed at right angles to the `center line, malte an acute angle with a line perpendicular to such center line. 1When the material is fed forward by the rollers ll, this arrangement ot rollers causes lll@ llld

lltl

lill

stand tolanother is not disturbed.

it to travel sid'ewise as Well as forward. The sidewisemovement 'carries it against a slde guide 12 so that the material vis roperly aligned to enter the succeeding stan s. This particular form of roll table is no part of the present invention, and is more particularly described and claimed in the cepending application of Florence C. Biggert, Jr., Serial N o. 236,409, filed November 29, 1927.

From the roll table 11 the material passe-i through successive Stands 13", 13", 13, 13, 13e and 13'. Each stand comprises two working rolls each having a backing roll of larger diameter. The backing roll necks are provided with roller bearings. Each stand is driven b an independent motor through gearing an pinions similar to the drive provided ior the stands 6, 6 and 6b. One of these drives is shown in enlarged diagram in Figure 2. The stands 13, 13b, 13, 13d, 13" and 13c are operated at successively higher speeds and form a continuous mill in which the material is subjected to successive reductions and issues as a long, straight strip sheet.

The .n-iaterial produced by the mill is so thin and wide that its direction of travel between stands cannot be controlled by side guides. The anti-fraction bearings provided for the necks of the backing rolls areeii'ective for maintaining the contour of the backing 4rolls within such limits that the proper direction of the material from one stands are arranged so that material if fed fronr one stand to the other in a substantially direct line.

Figures 3`to 8 inclusive show one of the fourhigh stands in detail. Each stand comprises working rolls 15 backed by larger rolls 16. As above stated, power is supplied tothe rolls 15 through spindles 10. The wobbler connections `are shown t 17 in Figure 3. y Eachbacking roll 16 is provided with vroller bearings indicated generally by the reference characters 18 and 19. The backing rolls are not positively'driven, butare nevertheless provided with drive connections 20 which are used when the rolls are turned, or in case they are redressed.

The bearings 18 and 19 each have aspaee'r ring 21 abutting the roll body. The inner ,race 22 fits against this ring. Each outer race 23 is carried in a. case` 24 which fits in a window of the mill housingv 25. Bearing rollers v26 spaced from one anotherlby cages 27 lie between the inner and outer races.

` The outer race of the bearing 18 bears at its innerend against a shoulder 28 formed in 'the case 24 and is held in place by a spacer 29 having an inner sleeve portion 30 connected by ribs 31 to an' outel` flange portion 32. This outer flange portion is secured by The studs 33 to the case 24. The inner race of the bearinnr 18 is held in place by a spacer ring 34. 'lthe backin roll necks are recessed near their outer en s to receive half rings 35. These half rings are threaded on their outer faces to receive a retainer 36. The retainer is screwed ti htly against the spacer ring 34 and is held 1n place by one or more screws 37 extending through the retainer rings 36 into the spacer 34.

Felt rings 38l are provided between the rings 21 and the case 24 and between the spacer ring 34 and the flange 32 to prevent ingress of dirt.

Each bearing 19 is designed to resist end thrust as well as radial load. The provision of anti-friction means for resisting end thrust is relatively less important than the provision of anti-friction means for taking the radial load. However, the space provided nlakes the hereinafter described end thrust bearing easy of application.

A spacer ring 39 lits around the roll neck and abuts the inner race 22 of each bearing 19. A thrust ring 40 fits against the spacer ring 39 and 'a spacer ring 34a lies outside the thrust ring 40. The spacer ring 34` is held in place in exactly the same manner as is the spacer ring 34 of the bearing 18.

On either side of the thrust ring 40 there are provided thrust resisting rollers 41 carried in cages 42. Outer thrust rings 43 andl 43b are provided. The thrust ring 43 bears against the race 23, and the thrust ring 43b is held in place by a flange 32, The flange '32 is held in place by studs 33.

This thrust bearing definitely positions .one end of the backing-roll. It will be noted from Figure 6 that the bearing 18 permits end play and thus takes care of longitudinal expansion or contraction of the roll.

Figuresf and 8 show the bearings for the working rolls 15. These bearings need only resist the sidewise thrust and ordinary .brasses sutiice for this. The apparatus shown in Figures 7 and 8 provides a convenient way of aligning the working rolls.

The lower working roll 15 rests on its backing roll 16 and bra'sses 44 engage all its necks or opposite sides. The brasses 44 at each end of the roll are supported by a hollow casting 45. This casting fits in the Window of the mill housing and is held in place by clamp fingers 46.

lThe upper working roll `is similarly mounted, except that it is additionally provided with brasses 47 below thegnecks. The brasses 47 provide a bearing support for the upper roll when the mill is statlonary or is running idle.

The brasses 44 engage the ends of the-- working roll bodies as shown in Figure 8. These brasses are backed by plates 48 whose inner ends engage shoulders 49. formed on the brasses 44. Clamping lingers 50 carried lib till

is also provided. Wedges 52 lie on either side of each working roll neck. These wedges are inside the hollow castings and are adjustable toward or away from the center of the mill by bolts 53 which extend through openings in the hollow castings, and are provided with adjusting nuts 54. Wedge blocks 55 lie o n either side of each wedge 52. The outer wedge blocks are stationary, but, the inner ones bear against the plates 48 and transmit' force -rom the wedges. By adjusting the wedges on opposite sides of a roll neck, one inwardly and the other outwardly, a side -wise adjustment of that end ot the roll is eiected.

The lower backing roll and its working roll are not arranged lor vertical adjustment, the casings 24 resting on the housings 25 at the bottoms of their windows. The upper rolls are adjustable to` permit otrolling different gauges. 'lhis adjustment is ettected by screws 56 operated through gearin by screw-down motors 57. i

alance springs 58 are provided for the upper rolls. 'lhese springs rest on forks 59 termed in the mill housings and are con lnected throu h litt rods d@ to slides til.

These slides ave ledges 62 (Figure 7) at their bottom ends, whichledges engage the castings 45 tor the upper working rolls.

lille have shown and described the preterred embodiment ot our invention, but it will be understood that it is not limited to the lorm shown, but ma be otherwise ern-- bodied or practiced within the scope et the tollowing claims.

l. ln the method oit rolling thin sheet or strip material in a mill having working rolls, and backing rolls, ot larger diameter, Ylor the working rolls, the steps consisting in limiting the rise in temperature ot the backing roll necks to such a' oint that varia tions in the contour olf t e backing rolls are controlled within such limits as to substantially prevent buckling or wrinkling oi' the thin material passed between the working rolls. 2. lntbe method'of rolling thin sheet or strip material in a mill having working rolls, and backing rolls, oi larger diameter 'tor 'the working rolls, the steps consisting in 'supplving rolling power through the working ro s and limiting the rise in temperature ol the vbacking roll necks to such a point that variations in the contour of the backing rolls are controlled within such limits as to'substantially prevent buckling or wrinkling ot the thin material passed between the vworku ing rolls..

3. A mill for rolling material of substantially uniform thickness, comprising at least two working rolls provided with backing rolls of larger diameter, the backing rolls having necks of sutiicient size to withstand the rolling pressure, and anti-friction bearings 'or said backing roll necks, the diameter oit'. the backing roll body relative to the diameter ot the working roll being such as to permit of using anti-friction bearings of sufficient size to withstand the rolling pressure.

4. 'A mill for rolling material of substair tially uniform thickness, comprising workn ing rolls provided with backing rolls ol larger diameter, the backing rolls having necks of suliicient size to withstand the rolle ing pressure, anti-friction bearings tor said. backing roll necks, the diameter of the backing roll body relative to the diameter ot the working roll being such as to permit ot using anti-friction bearings of sumcient size to withstand the rolling pressure, a working roll having a neck extending between the anti-friction bearings ot the ybacking rolls, and means tor supplying rolling power through the working roll neck.

5. A mill tor rolling material ont substarr tially uniform thickness, com rising working rolls having backing ro ls ot larger diameter, thebacking rolls havin 4necks of sufficient size to withstand the ro ling `pressure, and anti-friction bearings tor said backing roll necks, the diameter oit the backing roll body relative to the diameter ol the working roll being such. as to permit ot using antiftrictionl bearings oit sumcient sise to withstand the rolling pressure, at least one of said anti-triction bearings being so lilormed as to oppose endwise thrust oitthe backing roll. i

d. ln the method ol rolling thin sheet or strip material in a mill having working rolls provided with backing rolls ot larger diameter, the step consisting in maintaining the temperature of the backing roll necks below a point where expansion of a backing roll body induced by heat in the roll necks causes variation and consequent buckling or wrinkling ot the product.

7. A mill for rolling thin strips or sheets havingI working rolls and -backmg rolls of larger diameter, the working rolls being substantially uniformly spaced apart and delining a pass of such width and thinness that material heating of theY backing roll necks would canse such unequal expansion ot a backing roll body as would distort the pass vsufficiently to cause buckling or-wrin- `kling ot the thin product, and anti-friction bearings tor the backing-.rolls, whereby lthe temperature -of the backing roll necks is maintained suiiicientlydow to substantially obviate suchv unequal expansion as would canse `such buckling or wrinkling.

fill

llti

l liti lill llilll 8. A rolling mill formaterial of substantially uniform'thickness, the mill being of such width that the available space in a two high mill of the same width would prevent the use of roller bearings ofthe necessary load carrying capacity, comprising large y backingP rolls `with necks, intermediate workin rolls, means for drivin the working 'rol s, `and anti-friction bearings for the backing rolls, the anti-friction bearings having outer races encircling the necks, the

intermediate working rolls being of Sulliciently small diameter to reduce the spreading force in the mill to such' point that the anti-friction bearings emploed re uire a smaller space than those whic woul be re.-

u quired in a-two high mill of the same width,

whereb the outer races of the bearings for the bac ing rolls are suiliciently spaced apart to allow room for the driving means.

' v9. A continuous mill for rolling material of substantially uniform thickness, comprising a plurality of stands having working rolls provided with backin rolls of llargier diameter, the backing ro ls having nec s of s'uicie'nt size to withstand the rolling pressure, and anti-friction bearings for sald backin roll necks, the diameter of the backing rol? bodies relative to the diameter of the working rolls being such as to permit of using anti-friction bearings of suiiicient Vsubstantially uniform thickness in a mill com rising a plurality of stands having wor ing rolls provided with lbacking rolls of larger diameter, the steps consisting in passing a piece of material thru the mill so that during at least a portion ofthe roll;-

ing operation it is being rolled simultaneously in at least two stands, and maintaining the temperature of the i backing roll necks below a point where expansion of av vbacking roll body induced by heat in the roll .neck causes detrimental variation in the product.

11. In the-method of lrolling thin material of substantially uniform thickness in a continuous mill comprising a pluralit ofl temperature of the backing roll necks to such a point that variations in the contour of the backing rolls are controlled within such limits as to substantially prevent buckling or wrinkling of the thin material passed between the working rolls, such as would be consequent upon variation of the .contour of the backing rolls'in the several stands.

12. -A mill for producing thin, wide, rolled material of substantlally uniform thickness, comprising Va plurality of stands having working rolls and backing rolls of larger diameter, the mill operating to reduce the material to such thinness that its direction of travel between continuous stands could not be controlled by side guides, and anti-friction bearings for the necks of the backing rolls, whereby the contour of the backing rolls in a stand is not varied by roll neck heating to such an extent as to interfere with the proper direction of the material in a substantially direct line -to a succeeding stand, theistands being arranged to successively act on the material.

13. A rolling'mill comprising a series of stands of rolls arranged to successively engage a piece of material to be rolled, each stand belng composed of working rolls, backing rolls of larger diameter, and means for applying power to the workin rolls, said mill defining successive passes 0% such width and effective for taking such drafts that the product of the mill is of such width and thinness that sli ht variations of roll contour such as wou d. be due to variation arising froinchange of temperature of the backing roll necks would buckle or wrinkle the piece durinfr its passage through the mill, and anti-frlction bearings for the backing rolls whereby such buckling or wrinkling is avoided.

set our hands.

\ FLORENCE C.'BIGGERT, JR.

LANE J OHNSQN.

In testimony whereof we have hereunto 

